No IP address for a successful connection on LTE modem

[Garfield Watkins]

I have created a plugin for an LTE modem. This modem exposes 1 AT command port (e.g. ttyUSB0) and one ethernet port via usb (cdc_ether).

When the modem is inserted via USB, the kernel enumerates some serial ports(ttyUSB0 -> ttyUSB7) and a network interface (enp0s20f0u1)

The modem establishes a default bearer on network registration and to establish a data network connection I need to create a pdp context (AT+CGDCONT) with an APN and thereafter activate it with AT+CGACT=1,1

The modem, which is configured in router mode responds by activating its internal dhcp server causing network managers dhcp client to work its magic and eventually configure the ethernet port with all the info it needs (gateways, dns servers, ip address etc).

This same process is essentially performed by my plugin and yet no IP address get assigned to the ethernet adapter exposed by the modem.

Why could this be happening ?

My plugin, specifically the bearer interface implements the folloiwing:

broadband_bearer_class->dial_3gpp = dial_3gpp;

broadband_bearer_class->dial_3gpp_finish = dial_3gpp_finish;

broadband_bearer_class->disconnect_3gpp = disconnect_3gpp;

broadband_bearer_class->disconnect_3gpp_finish = disconnect_3gpp_finish;

broadband_bearer_class->get_ip_config_3gpp = get_ip_config_3gpp;

broadband_bearer_class->get_ip_config_3gpp_finish = get_ip_config_3gpp_finish;

Regards